Abstract:We obtain the density variation in the crust from the Jiuzhaigou MS 7.0 earthquake in 2017, deriving it from the dynamic variation of gravity in 2014~2017, using the compact gravity inversion method: (1) before the Jiuzhaigou MS7.0 earthquake, variation of gravity in the large space range appears in the survey area, while forming a high gradient zone of gravity change along the Zhangye-Xining-Jiuzhaigou; (2) the density variation in the crust increases with depth, and is up to 0.2 g/cm3 at 45 km depth around; (3) during the early period before the MS7.0 Jiuzhaigou earthquake (2014-04~2017-04), regional density variation is distributed in a four-quadrant form. The materials migration is dominated by left-lateral strike motion, which is same as the focal mechanism solutions. The results show the tectonic movement related to the occurrence of this earthquake before the Jiuzhaigou earthquake, and that strong earthquakes occur easily in places where material migration is concentrated.
WANG Jiapei,SHEN Chongyang,XUAN Songbai et al. Density Variation in the Crust before the Jiuzhaigou, Sichuan, MS7.0 Earthquake of 2017[J]. jgg, 2018, 38(8): 771-776.